3. Behind the Curtain Music and the Mind Machine 1 2 3 4 5 6 7 8 9 10 11 12 13 14 co 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 S 33 R 34 4th Pass Pages For cognitive scientists, the word mind refers to that part of each ofus that embodies our thoughts, hopes, desires, memories, beliefs, and experiences. The brain, on the other hand, is an organ of the body, a collection of cells and water, chemicals and blood vessels, that resides in the skull. Activity in the brain gives rise to the contents of the mind. Cognitive scientists sometimes make the analogy that the brain is like a computer’s CPU, or hardware, while the mind is like the programs or software running on the CPU. (If only that were literally true and we could just run out to buy a memory upgrade.) Different programs can run on what is essentially the same hardware—different minds can arise from very similar brains. Western culture has inherited a tradition of dualism from René Descartes, who wrote that the mind and the brain are two entirely sepa- rate things. Dualists assert that the mind preexisted, before you were born, and that the brain is not the seat of thought—rather, it is merely an instrument of the mind, helping to implement the mind’s will, move mus- cles, and maintain homeostasis in the body. To most of us, it certainly feels as though our minds are something unique and distinctive, separate from just a bunch of neurochemical processes. We have a feeling of what it is like to be me, what it is like to be me reading a book, and what it is 18828_01_1-270_r9kp.qxd 5/23/06 3:18 PM Page 81 like to think about what it is like to be me. How can me be reduced so un- ceremoniously to axons, dendrites, and ion channels? It feels like we are something more. But this feeling could be an illusion, just as it certainly feels as though the earth is standing still, not spinning around on its axis at a thousand miles per hour. Most scientists and contemporary philosophers believe that the brain and mind are two parts of the same thing, and some be- lieve that the distinction itself is flawed. The dominant view today is that that the sum total of your thoughts, beliefs, and experiences is repre- sented in patterns of firings—electrochemical activity—in the brain. If the brain ceases to function, the mind is gone, but the brain can still ex- ist, thoughtless, in a jar in someone’s laboratory. Evidence for this comes from neuropsychological findings of regional specificity of function. Sometimes, as a result of stroke (a blockage of blood vessels in the brain that leads to cell death), tumors, head injury, or other trauma, an area of the brain becomes damaged. In many of these cases, damage to a specific brain region leads to a loss of a particular mental or bodily function. When dozens or hundreds of cases show loss of a specific function associated with a particular brain region, we infer that this ...

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For cognitive scientists, the word mind refers to that part of
each ofus that embodies our thoughts, hopes, desires, memories,
beliefs,
and experiences. The brain, on the other hand, is an organ of the
body,
a collection of cells and water, chemicals and blood vessels,
that resides
in the skull. Activity in the brain gives rise to the contents of
the mind.
Cognitive scientists sometimes make the analogy that the brain
is like a
computer’s CPU, or hardware, while the mind is like the
programs or
software running on the CPU. (If only that were literally true
and we
could just run out to buy a memory upgrade.) Different
programs can
run on what is essentially the same hardware—different minds
can arise
from very similar brains.
Western culture has inherited a tradition of dualism from René

4. Descartes, who wrote that the mind and the brain are two
entirely sepa-
rate things. Dualists assert that the mind preexisted, before you
were
born, and that the brain is not the seat of thought—rather, it is
merely an
instrument of the mind, helping to implement the mind’s will,
move mus-
cles, and maintain homeostasis in the body. To most of us, it
certainly
feels as though our minds are something unique and distinctive,
separate
from just a bunch of neurochemical processes. We have a
feeling of what
it is like to be me, what it is like to be me reading a book, and
what it is
18828_01_1-270_r9kp.qxd 5/23/06 3:18 PM Page 81
like to think about what it is like to be me. How can me be
reduced so un-
ceremoniously to axons, dendrites, and ion channels? It feels
like we are
something more.

5. But this feeling could be an illusion, just as it certainly feels as
though
the earth is standing still, not spinning around on its axis at a
thousand
miles per hour. Most scientists and contemporary philosophers
believe
that the brain and mind are two parts of the same thing, and
some be-
lieve that the distinction itself is flawed. The dominant view
today is that
that the sum total of your thoughts, beliefs, and experiences is
repre-
sented in patterns of firings—electrochemical activity—in the
brain. If
the brain ceases to function, the mind is gone, but the brain can
still ex-
ist, thoughtless, in a jar in someone’s laboratory.
Evidence for this comes from neuropsychological findings of
regional
specificity of function. Sometimes, as a result of stroke (a
blockage of
blood vessels in the brain that leads to cell death), tumors, head
injury,

6. or other trauma, an area of the brain becomes damaged. In many
of these
cases, damage to a specific brain region leads to a loss of a
particular
mental or bodily function. When dozens or hundreds of cases
show loss
of a specific function associated with a particular brain region,
we infer
that this brain region is somehow involved in, or perhaps
responsible for,
that function.
More than a century of such neuropsychological investigation
has
allowed us to make maps of the brain’s areas of function, and to
local-
ize particular cognitive operations. The prevailing view of the
brain is
that it is a computational system, and we think of the brain as a
type of
computer. Networks of interconnected neurons perform
computations
on information and combine their computations in ways that
lead to
thoughts, decisions, perceptions, and ultimately consciousness.

7. Differ-
ent subsystems are responsible for different aspects of
cognition. Dam-
age to an area of the brain just above and behind the left ear—
Wernicke’s
area—causes difficulty in understanding spoken language;
damage to a
region at the very top of the head—the motor cortex—causes
difficulty
moving your fingers; damage to an area in the center of the
brain—the
hippocampal complex—can block the ability to form new
memories,
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while leaving old memories intact. Damage to an area just
behind your
forehead can cause dramatic changes in personality—it can rob
aspects
of you from you. Such localization of mental function is a
strong scien-
tific argument for the involvement of the brain in thought, and
the thesis

10. that thoughts come from the brain.
We have known since 1848 (and the medical case of Phineas
Gage)
that the frontal lobes are intimately related to aspects of self
and per-
sonality. Yet even one hundred and fifty years later, most of
what we can
say about personality and neural structures is vague and quite
general.
We have not located the “patience” region of the brain, nor the
“jealousy”
or “generous” regions, and it seems unlikely that we ever will.
The brain
has regional differentiation of structure and function, but
complex per-
sonality attributes are no doubt distributed widely throughout
the brain.
The human brain is divided up into four lobes—the frontal,
temporal,
parietal, and occipital—plus the cerebellum. We can make some
gross
generalizations about function, but in fact behavior is complex
and not
readily reducible to simple mappings. The frontal lobe is

11. associated with
planning, and with self-control, and with making sense out of
the dense
and jumbled signals that our senses receive—the so-called
“perceptual
organization” that the Gestalt psychologists studied. The
temporal lobe
is associated with hearing and memory. The parietal lobe is
associated
with motor movements and spatial skill, and the occipital lobe
with vi-
sion. The cerebellum is involved in emotions and the planning
of move-
ments, and is the evolutionarily oldest part of our brain; even
many
animals, such as reptiles, that lack the “higher” brain region of
the cortex
still have a cerebellum. The surgical separation of a portion of
the frontal
lobe, the prefrontal cortex, from the thalamus is called a
lobotomy. So
when the Ramones sang “Now I guess I’ll have to tell ’em /
That I got
no cerebellum” in their song “Teenage Lobotomy” (words and

12. music by
Douglas Colvin, John Cummings, Thomas Erdely, and Jeffrey
Hyman)
they were not being anatomically accurate, but for the sake of
artistic li-
cense, and for creating one of the great rhymes in rock music, it
is hard
to begrudge them that.
Musical activity involves nearly every region of the brain that
we
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know about, and nearly every neural subsystem. Different
aspects of the
music are handled by different neural regions—the brain uses
functional
segregation for music processing, and employs a system of
feature de-
tectors whose job it is to analyze specific aspects of the musical
signal,
such as pitch, tempo, timbre, and so on. Some of the music
processing
has points in common with the operations required to analyze

15. other
sounds; understanding speech, for example, requires that we
segment
a flurry of sounds into words, sentences, and phrases, and that
we be
able to understand aspects beyond the words, such as sarcasm
(isn’t
that interesting). Several different dimensions of a musical
sound need
to be analyzed—usually involving several quasi-independent
neural
processes—and they then need to be brought together to form a
coher-
ent representation of what we’re listening to.
Listening to music starts with subcortical (below-the-cortex)
struc-
tures—the cochlear nuclei, the brain stem, the cerebellum—and
then
moves up to auditory cortices on both sides of the brain. Trying
to follow
along with music that you know—or at least music in a style
you’re fa-
miliar with, such as baroque or blues—recruits additional
regions of the

16. brain, including the hippocampus—our memory center—and
subsec-
tions of the frontal lobe, particularly a region called inferior
frontal cor-
tex, which is in the lowest parts of the frontal lobe, i.e., closer
to your
chin than to the top of your head. Tapping along with music,
either actu-
ally or just in your mind, involves the cerebellum’s timing
circuits. Per-
forming music—regardless of what instrument you play, or
whether you
sing, or conduct—involves the frontal lobes again for the
planning of
your behavior, as well as the motor cortex in the parietal lobe
just un-
derneath the top of your head, and the sensory cortex, which
provides
the tactile feedback that you have pressed the right key on your
instru-
ment, or moved the baton where you thought you did. Reading
music in-
volves the visual cortex, in the back of your head in the
occipetal lobe.

17. Listening to or recalling lyrics invokes language centers,
including Bro-
ca’s and Wernicke’s area, as well as other language centers in
the tempo-
ral and frontal lobes.
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At a deeper level, the emotions we experience in response to
music
involve structures deep in the primitive, reptilian regions of the
cerebel-
lar vermis, and the amygdala—the heart of emotional processing
in the
cortex. The idea of regional specificity is evident in this
summary but a
complementary principle applies as well, that of distribution of
function.
The brain is a massively parallel device, with operations
distributed
widely throughout. There is no single language center, nor is
there a sin-
gle music center. Rather, there are regions that peform
component oper-

20. ations, and other regions that coordinate the bringing together
of this
information. Finally, we have discovered only recently that the
brain has
a capacity for reorganization that vastly exceeds what we
thought be-
fore. This ability is called neuroplasticity, and in some cases, it
suggests
that regional specificity may be temporary, as the processing
centers for
important mental functions actually move to other regions after
trauma
or brain damage.
It is difficult to appreciate the complexity of the brain because
the num-
bers are so huge they go well beyond our everyday experience
(unless
you are a cosmologist). The average brain consists of one
hundred bil-
lion (100,000,000,000) neurons. Suppose each neuron was one
dollar,
and you stood on a street corner trying to give dollars away to
people as

21. they passed by, as fast as you could hand them out—let’s say
one dollar
per second. If you did this twenty-four hours a day, 365 days a
year, with-
out stopping, and if you had started on the day that Jesus was
born, you
would by the present day only have gone through about two
thirds of
your money. Even if you gave away hundred-dollar bills once a
second,
it would take you thirty-two years to pass them all out. This is a
lot of
neurons, but the real power and complexity of the brain (and of
thought)
come through their connections.
Each neuron is connected to other neurons—usually one
thousand to
ten thousand others. Just four neurons can be connected in
sixty-three
ways, or not at all, for a total of sixty-four possibilities. As the
number of
neurons increases, the number of possible connections grows
exponen-
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24. tially (the formula for the way that n neurons can be connected
to each
other is 2(n*(n-1)/2)):
For 2 neurons there are 2 possibilities for how they can be
connected
For 3 neurons there are 8 possibilities
For 4 neurons there are 64 possibilities
For 5 neurons there are 1,024 possibilities
For 6 neurons there are 32,768 possibilities
The number of combinations becomes so large that it is unlikely
that
we will ever understand all the possible connections in the
brain, or
what they mean. The number of combinations possible—and
hence the
number of possible different thoughts or brain states each of us
can
have—exceeds the number of known particles in the entire
known uni-
verse.

25. Similarly, you can see how it is that all the songs we have ever
heard—and all those that will ever be created—could be made
up of just
twelve musical notes (ignoring octaves). Each note can go to
another
note, or to itself, or to a rest, and this yields twelve
possibilities. But each
of those possibilities yields twelve more. When you factor in
rhythm—
each note can take on one of many different note lengths—the
number
of possibilities grows very, very rapidly.
Much of the brain’s computational power comes from this
enormous
possibility for interconnection, and much of it comes from the
fact that
brains are parallel processing machines, rather than serial
processors. A
serial processor is like an assembly line, handling each piece of
informa-
tion as it comes down the mental conveyor belt, performing
some oper-
ation on that piece of information, and then sending it down the
line for

26. the next operation. Computers work like this. Ask a computer to
down-
load a song from a Web site, tell you the weather in Boise, and
save a file
you’ve been working on, and it will do them one at a time; it
does things
so fast that it can seem as though it is doing them at the same
time—in
parallel—but it isn’t. Brains, on the other hand, can work on
many things
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at once, overlapping and in parallel. Our auditory system
processes
sound in this way—it doesn’t have to wait to find out what the
pitch of a
sound is to know where it is coming from; the neural circuits
devoted to
these two operations are trying to come up with answers at the
same
time. If one neural circuit finishes its work before another, it
just sends
its information to other connected brain regions and they can

29. begin us-
ing it. If late-arriving information that affects an interpretation
of what
we’re hearing comes in from a separate processing circuit, the
brain can
“change its mind” and update what it thinks is out there. Our
brains are
updating their opinions all the time—particularly when it comes
to per-
ceiving visual and auditory stimuli—hundreds of times per
second, and
we don’t even know it.
Here’s an analogy to convey how neurons connect to each other.
Imagine that you’re sitting home alone one Sunday morning.
You don’t
feel much of one way or another—you’re not particularly happy,
not par-
ticularly sad, neither angry, excited, jealous, nor tense. You feel
more or
less neutral. You have a bunch of friends, a network of them,
and you can
call any of them on the phone. Let’s say that each of your
friends is rather

30. one dimensional and that they can exert a great influence on
your mood.
You know, for example, that if you telephone your friend
Hannah she’ll
put you in a happy mood. Whenever you talk to Sam it makes
you sad,
because the two of you had a third friend who died and Sam
reminds you
of that. Talking to Carla makes you calm and serene, because
she has a
soothing voice and you’re reminded of the times you sat in a
beautiful
forest clearing with her, soaking up the sun and meditating.
Talking to
Edward makes you feel energized; talking to Tammy makes you
feel
tense. You can pick up your telephone and connect to any of
these
friends and induce a certain emotion.
You might have hundreds or thousands of these one-dimensional
friends, each capable of evoking a particular memory,
experience, or
mood state. These are your connections. Accessing them causes
you to

31. change your mood, or state. If you were to talk to Hannah and
Sam at the
same time, or one right after the other, Hannah would make you
feel
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happy, Sam would make you feel sad, and in the end you’d be
back to
where you were—neutral. But we can add an additional nuance,
which
is the weight or force-of-influence of these connections—how
close you
feel to an individual at a particular point in time. That weight
determines
the amount of influence the person will have on you. If you feel
twice as
close to Hannah as you do to Sam, talking to Hannah and Sam
for an
equal amount of time would still leave you feeling happy,
although not as
happy as if you had talked to Hannah alone—Sam’s sadness
brings you
down, but only halfway from the happiness you gained from

34. talking to
Hannah.
Let’s say that all of these people can talk to one another, and in
so do-
ing, their states can be modified to some extent. Although your
friend
Hannah is dispositionally cheery, her cheerfulness can be
attenuated by
a conversation she has with Sad Sam. If you phone Edward the
energizer
after he’s just spoken with Tense Tammy (who has just gotten
off the
phone with Jealous Justine), Edward may make you feel a new
mix of
emotions you’ve never experienced before, a kind of tense
jealousy that
you have a lot of energy to go out and do something about. And
any of
these friends might telephone you at any time, evoking these
states in
you as a complex chain of feelings or experiences that has gone
around,
each one influencing the other, and you, in turn, will leave your
emo-

35. tional mark on them. With thousands of friends interconnected
like this,
and a bunch of telephones in your living room ringing off the
hook all
day long, the number of emotional states you might experience
would in-
deed be quite varied.
It is generally accepted that our thoughts and memories arise
from
the myriad connections of this sort that our neurons make. Not
all neu-
rons are equally active at one time, however—this would cause
a ca-
cophony of images and sensations in our heads (in fact, this is
what
happens in epilepsy). Certain groups of neurons—we can call
them net-
works—become active during certain cognitive activities, and
they in
turn can activate other neurons. When I stub my toe, the sensory
recep-
tors in my toe send signals up to the sensory cortex in my brain.
This sets

36. off a chain of neural activations that causes me to experience
pain, with-
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draw my foot from the object I stubbed it against, and that
might cause
my mouth to open involuntarily and shout “& % @ !”
When I hear a car horn, air molecules impinging on my eardrum
cause
electrical signals to be sent to my auditory cortex. This causes a
cascade
of events that recruits a very different group of neurons than toe
stub-
bing. First, neurons in the auditory cortex process the pitch of
the sound
so that I can distinguish the car horn from something with a
different
pitch like a truck’s air horn, or the air-horn-in-a-can at a
football game. A
different group of neurons is activated to determine the location
from
which the sound came. These and other processes invoke a
visual ori-

39. enting response—I turn toward the sound to see what made it,
and in-
stantaneously, if necessary, I jump back (the result of activity
from the
neurons in my motor cortex, orchestrated with neurons in my
emotional
center, the amygdala, telling me that danger is imminent).
When I hear Rachmaninoff’s Piano Concerto no. 3, the hair
cells in
my cochlea parse the incoming sound into different frequency
bands,
sending electrical signals to my primary auditory cortex—area
A1—
telling it what frequencies are present in the signal. Additional
regions in
the temporal lobe, including the superior temporal sulcus and
the supe-
rior temporal gyrus on both sides of the brain, help to
distinguish the
different timbres I’m hearing. If I want to label those timbres,
the hip-
pocampus helps to retrieve the memory of similar sounds I’ve
heard
before, and then I’ll need to access my mental dictionary—

40. which will
require using structures found at the junction between the
temporal,
occipetal, and parietal lobes. So far, these regions are the same
ones,
although activated in different ways and with different
populations
of neurons, that I would use to process the car horn. Whole new
popula-
tions of neurons will become active, however, as I attend to
pitch
sequences (dorsalateral prefrontal cortex, and Brodmann areas
44
and 47), rhythms (the lateral cerebellum and the cerebellar
vermis), and
emotion (frontal lobes, cerebellum, the amygdala, and the
nucleus
accumbens—part of a network of structures involved in feelings
of plea-
sure and reward, whether it is through eating, having sex, or
listening to
pleasurable music).
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43. To some extent, if the room is vibrating with the deep sounds of
the
double bass, some of those same neurons that fired when I
stubbed my
toe may fire now—neurons sensitive to tactile input. If the car
horn has
a pitch of A440, neurons that are set to fire when that frequency
is en-
countered will most probably fire, and they’ll fire again when
an A440 oc-
curs in Rachmaninoff. But my inner mental experience is likely
to be
different because of the different contexts involved and the
different
neural networks that are recruited in the two cases.
My experience with oboes and violins is different, and the
particular
way that Rachmaninoff uses them may cause me to have the
opposite
reaction to his concerto than I have to the car horn; rather than
feeling
startled, I feel relaxed. The same neurons that fire when I feel
calm and

44. safe in my environment may be triggered by the calm parts of
the con-
certo.
Through experience, I’ve learned to associate car horns with
danger,
or at least with someone trying to get my attention. How did
this hap-
pen? Some sounds are intrinsically soothing while others are
frighten-
ing. Although there is a great deal of interpersonal variation, we
are born
with a predisposition toward interpreting sounds in particular
ways.
Abrupt, short, loud sounds tend to be interpreted by many
animals as an
alert sound; we see this when comparing the alert calls of birds,
rodents,
and apes. Slow onset, long, and quieter sounds tend to be
interpreted as
calming, or at least neutral. Think of the sharp sound of a dog’s
bark, ver-
sus the soft purring of a cat who sits peacefully on your lap.
Composers

45. know this, of course, and use hundreds of subtle shadings of
timbre and
note length to convey the many different emotional shadings of
human
experience.
In the “Surprise Symphony” by Haydn (Symphony no. 94 in G
Major,
second movement, andante), the composer builds suspense by
using
soft violins in the main theme. The softness of the sound is
soothing, but
the shortness of the pizzicato accompaniment sends a gentle,
contradic-
tory message of danger, and together they give a soft sense of
suspense.
The main melodic idea spans barely more than half an octave, a
perfect
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fifth. The melodic contour further suggests complacency—the
melody
first goes up, then down, then repeats the “up” motif. The
parallelism im-

48. plied by the melody, the up/down/up, gets the listener ready for
another
“down” part. Continuing with the soft, gentle violin notes, the
maestro
changes the melody by going up—just a little—but holds the
rhythms
constant. He rests on the fifth, a relatively stable tone
harmonically. Be-
cause the fifth is the highest note we’ve encountered so far, we
expect
that when the next note comes in, it will be lower—that it will
begin the
return home toward the root (or tonic), and “close the gap”
created by
the distance between the tonic and the current note—the fifth.
Then,
from out of nowhere, Haydn sends us a loud note an octave
higher, with
the brash horns and timpani carrying the sound. He has violated
our ex-
pectations for melodic direction, for contour, for timbre, and for
loud-
ness all at once. This is the “Surprise” in the “Surprise
Symphony.”

49. This Haydn symphony violates our expectations of how the
world
works. Even someone with no musical knowledge or musical
expecta-
tions whatsoever finds the symphony surprising because of this
timbral
effect, switching from the soft purring of the violins to the alert
call of
horns and drums. For someone with a musical background, the
sym-
phony violates expectations that have been formed based on
musical
convention and style. Where do surprises, expectations, and
analyses of
this sort occur in the brain? Just how these operations are
carried out in
neurons is still something of a mystery, but we do have some
clues.
Before going any farther, I have to admit a bias in the way I
approach the
scientific study of minds and brains: I have a definite
preference for
studying the mind rather than the brain. Part of my preference is
per-

50. sonal rather than professional. As a child I wouldn’t collect
butterflies
with the rest of my science class because life—all life—seems
sacred to
me. And the stark fact about brain research over the course of
the last
century is that it generally involves poking around in the brains
of live
animals, often our close genetic cousins, the monkeys and apes,
and
then killing (they call it “sacrificing”) the animal. I worked for
one mis-
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erable semester in a monkey lab, dissecting the brains of dead
monkeys
to prepare them for microscopic examination. Every day I had
to walk
by cages of the ones that were still alive. I had nightmares.
At a different level, I’ve always been more fascinated by the
thoughts
themselves, not the neurons that give rise to them. A theory in
cogni-

53. tive science named functionalism—which many prominent
researchers
subscribe to—asserts that similar minds can arise from quite
different
brains, that brains are just the collection of wires and
processing mod-
ules that instantiate thought. Regardless of whether the
functionalist
doctrine is true, it does suggest that there are limits to how
much we can
know about thought from just studying brains. A neurosurgeon
once told
Daniel Dennett (a prominent and persuasive spokesperson for
function-
alism) that he had operated on hundreds of people and seen
hundreds of
live, thinking brains, but he had never seen a thought.
When I was trying to decide where to attend graduate school,
and
who I wanted to have as a mentor, I was infatuated with the
work of Pro-
fessor Michael Posner. He had pioneered a number of ways of
looking
at thought processes, among them mental chronometry (the idea

54. that
much can be learned about the organization of the mind by
measuring
how long it takes to think certain thoughts), ways to investigate
the
structure of categories, and the famous Posner Cueing
Paradigm, a novel
method for studying attention. But rumor had it that Posner was
aban-
doning the mind and had started studying the brain, something I
was cer-
tain I did not want to do.
Although still an undergraduate (albeit a somewhat older one
than
usual), I attended the annual meeting of the American
Psychological As-
sociation, which was held in San Francisco that year, just forty
miles up
the road from Stanford, where I was finishing up my B.A. I saw
Posner’s
name on the program and attended his talk, which was full of
slides con-
taining pictures of people’s brains while they were doing one
thing or an-

55. other. After his talk was over he took some questions, then
disappeared
out a back door. I ran around to the back and saw him way
ahead, rush-
ing across the conference center to get to another talk. I ran to
catch up
to him. I must have been quite a sight to him! I was out of
breath from
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running. Even without the panting, I was nervous meeting one
of the
great legends of cognitive psychology. I had read his textbook
in my first
psychology class at MIT (where I began my undergraduate
training be-
fore transferring to Stanford); my first psychology professor,
Susan
Carey, spoke of him with what could only be described as
reverence in
her voice. I can still remember the echoes of her words,
reverberating
through the lecture hall at MIT: “Michael Posner, one of the

58. smartest and
most creative people I’ve ever met.”
I started to sweat, I opened my mouth, and . . . nothing. I started
“Mmm . . .” All this time we were walking rapidly side by
side—he’s a fast
walker—and every two or three steps I’d fall behind again. I
stammered
an introduction and said that I had applied to the University of
Oregon to
work with him. I’d never stuttered before, but I had never been
this ner-
vous before. “P-p-p-professor P-p-posner, I hear that you’ve
shifted your
research focus entirely to the b-b-brain—is that true? Because I
really
want to study cognitive psychology with you,” I finally told
him.
“Well, I am a little interested in the brain these days,” he said.
“But I
see cognitive neuroscience as a way to provide constraints for
our theo-
ries in cognitive psychology. It helps us to distinguish whether
a model

59. has a plausible basis in the underlying anatomy.”
Many people enter neuroscience from a background in biology
or
chemistry and their principal focus is on the mechanisms by
which cells
communicate with each other. To the cognitive neuroscientist,
under-
standing the anatomy or physiology of the brain may be a
challenging
intellectual exercise (the brain scientists’ equivalent of a really
compli-
cated crossword puzzle), but it is not the ultimate goal of the
work. Our
goal is to understand thought processes, memories, emotions,
and expe-
riences, and the brain just happens to be the box that all this
happens in.
To return to the telephone analogy and conversations you might
have
with different friends who influence your emotions: If I want to
predict
how you’re going to feel tomorrow, it will be of only limited
value for me
to map the layout of the telephone lines connecting all the

60. different
people you know. More important is to understand their
individual pro-
clivities: Who is likely to call you tomorrow and what are they
likely to
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say? How are they apt to make you feel? Of course, to entirely
ignore the
connectivity question would be a mistake too. If a line is
broken, or if
there is no evidence of a connection between person A and
person B, or
if person C can never call you directly but can only influence
you
through person A who can call you directly—all this
information pro-
vides important constraints to a prediction.
This perspective influences the way I study the cognitive neuro-
science of music. I am not interested in going on a fishing
expedition to
try every possible musical stimulus and find out where it occurs
in the

63. brain; Posner and I have talked many times about the current
mad rush
to map the brain as just so much atheoretical cartography. The
point for
me isn’t to develop a map of the brain, but to understand how it
works,
how the different regions coordinate their activity together, how
the sim-
ple firing of neurons and shuttling around of neurotransmitters
leads to
thoughts, laughter, feelings of profound joy and sadness, and
how all
these, in turn, can lead us to create lasting, meaningful works of
art.
These are the functions of the mind, and knowing where they
occur
doesn’t interest me unless the where can tell us something about
how
and why. An assumption of cognitive neuroscience is that it
can.
My perspective is that, of the infinite number of experiments
that are
possible to do, the ones worth doing are those that can lead us
to a bet-

64. ter understanding of how and why. A good experiment is
theoretically
motivated, and makes clear predictions as to which one of two
or more
competing hypotheses will be supported. An experiment that is
likely to
provide support for both sides of a contentious issue is not one
worth
doing; science can only move forward by the elimination of
false or un-
tenable hypotheses.
Another quality of a good experiment is that it is generalizable
to
other conditions—to people not studied, to types of music not
studied,
and to a variety of situations. A great deal of behavioral
research is con-
ducted on only a small number of people (“subjects” in the
experiment),
and with very artificial stimuli. In my laboratory we use both
musicians
and nonmusicians whenever possible, in order to learn about the
broad-

65. est cross section of people. And we almost always use real-
world music,
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actual recordings of real musicians playing real songs, so that
we can
better understand the brain’s responses to the kind of music that
most
people listen to, rather than the kind of music that is found only
in the
neuroscientific laboratory. So far this approach has panned out.
It is
more difficult to provide rigorous experimental controls with
this ap-
proach, but it is not impossible; it takes a bit more planning and
careful
preparation, but in the long run, the results are worth it. In
using this nat-
uralistic approach, I can state with reasonable scientific
certainty that
we’re studying the brain doing what it normally does, rather
than what it
does when assaulted by rhythms without any pitch, or melodies
without

68. any rhythms. In an attempt to separate music into its
components, we
run the risk—if the experiments are not done properly—of
creating
sound sequences that are very unmusical.
When I say that I am less interested in the brain than in the
mind, this
does not mean that I have no interest in the brain. I believe that
we all
have brains, and I believe brains are important! But I also
believe similar
thoughts can arise from different brain architectures. By
analogy, I can
watch the same television program on an RCA, a Zenith, a
Mitsubishi,
even on my computer screen with the right hardware and
software. The
architectures of all these are sufficiently distinct from one
another that
the patent office—an organization charged with the
responsibility of de-
ciding when something is sufficiently different from something
else that

69. it constitutes an invention—has issued different patents to these
various
companies, establishing that the underlying architectures are
signifi-
cantly different. My dog Shadow has a very different brain
organization,
anatomy, and neurochemistry from mine. When he is hungry or
hurts his
paw, it is unlikely that the pattern of nerve firings in his brain
bears much
resemblance to the pattern of firings in my brain when I’m
hungry or stub
my toe. But I do believe that he is experiencing substantially
similar
mind states.
Some common illusions and misconceptions need to be set
aside.
Many people, even trained scientists in other disciplines, have
the strong
intuition that inside the brain there is a strictly isomorphic
representation
of the world around us. (Isomorphic comes from the Greek word
iso,
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72. meaning “same,” and morphus, meaning “form.”) The Gestalt
psycholo-
gists, who were right about a great many things, were among the
first to
articulate this idea. If you look at a square, they argued, a
square-shaped
pattern of neurons is activated in your brain. Many of us have
the intu-
ition that if we’re looking at a tree, the image of the tree is
somewhere
represented in the brain as a tree, and that perhaps seeing the
tree acti-
vates a set of neurons in the shape of a tree, with roots at one
end and
leaves at the other. When we listen to or imagine a favorite
song, it feels
like the song is playing in our head, over a set of neural
loudspeakers.
Daniel Dennett and V. S. Ramachandran have eloquently argued
that
there is a problem with this intuition. If a mental picture of
something

73. (either as we see it right now or imagine it in memory) is itself
a picture,
there has to be some part of our mind / brain that is seeing that
picture.
Dennett talks about the intuition that visual scenes are
presented on
some sort of a screen or theater in our minds. For this to be
true, there
would have to be someone in the audience of that theater
watching the
screen, and holding a mental image inside his head. And who
would that
be? What would that mental image look like? This quickly leads
to an
infinite regress. The same argument applies to auditory events.
No one
argues that it doesn’t feel like we have an audio system in our
minds.
Because we can manipulate mental images—we can zoom in on
them,
rotate them, in the case of music we can speed up or slow down
the song
in our heads—we’re compelled to think there is a home theater
in the

74. mind. But logically this cannot be true because of the infinite
regress
problem.
We are also under the illusion that we simply open our eyes
and—we
see. A bird chirps outside the window and we instantly hear.
Sensory
perception creates mental images in our minds—representations
of the
world outside our heads—so quickly and seamlessly that it
seems there
is nothing to it. This is an illusion. Our perceptions are the end
product
of a long chain of neural events that give us the illusion of an
instanta-
neous image. There are many domains in which our strongest
intuitions
mislead us. The flat earth is one example. The intuition that our
senses
give us an undistorted view of the world is another.
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It has been known at least since the time of Aristotle that our

77. senses
can distort the way we perceive the world. My teacher Roger
Shepard, a
perception psychologist at Stanford University, used to say that
when
functioning properly, our perceptual system is supposed to
distort the
world we see and hear. We interact with the world around us
through our
senses. As John Locke noted, everything we know about the
world is
through what we see, hear, smell, touch, or taste. We naturally
assume
that the world is just as we perceive it to be. But experiments
have
forced us to confront the reality that this is not the case. Visual
illusions
are perhaps the most compelling proof of sensory distortion.
Many of us
have seen these sorts of illusions as children, such as when two
lines of
the same length appear to be different lengths (the Ponzo
illusion).
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Roger Shepard drew an illusion he calls “Turning the Tables”

80. that is
related to the Ponzo. It’s hard to believe, but these tabletops are
identi-
cal in size and shape (you can check by cutting out a piece of
paper or
cellophane the exact shape of one and then placing it over the
other).
This illusion exploits a principle of our visual system’s depth
perception
mechanisms. Even knowing that it is an illusion does not allow
us to turn
off the mechanism. No matter how many times we view this
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continues to surprise us because our brains are actually giving
us misin-
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In the Kaniza illusion there appears to be a white triangle lying
on top
of a black-outlined one. But if you look closely, you’ll see that
there are
no triangles in the figure. Our perceptual system completes or

83. “fills in”
information that isn’t there.
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Why does it do this? Our best guess is that it was evolutionarily
adap-
tive to do so. Much of what we see and hear contains missing
informa-
tion. Our hunter-gatherer ancestors might have seen a tiger
partially
hidden by trees, or heard a lion’s roar partly obscured by the
sound of
leaves rustling much closer to us. Sounds and sights often come
to us as
partial information that has been obscured by other things in the
envi-
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information

84. would help us make quick decisions in threatening situations.
Better to
run now than sit and try to figure out if those two separate,
broken
pieces of sound were part of a single lion roar.
The auditory system has its own version of perceptual
completion.
The cognitive psychologist Richard Warren demonstrated this
particu-
larly well. He recorded a sentence, “The bill was passed by both
houses
of the legislature,” and cut out a piece of the sentence from the
record-
ing tape. He replaced the missing piece with a burst of white
noise
(static) of the same duration. Nearly everyone who heard the
altered
recording could report that they heard both a sentence and
static. But a
large proportion of people couldn’t tell where the static was!
The audi-
tory system had filled in the missing speech information, so that
the sen-
tence seemed to be uninterrupted. Most people reported that

85. there was
static and that it existed apart from the spoken sentence. The
static and
the sentence formed separate perceptual streams due to
differences in
timbre that caused them to group separately; Bregman calls this
stream-
ing by timbre. Clearly this is a sensory distortion; our
perceptual system
is telling us something about the world that isn’t true. But just
as clearly,
this has an evolutionary/adaptive value if it can help us make
sense of
the world during a life-or-death situation.
According to the great perception psychologists Hermann von
Helmholtz, Richard Gregory, Irvin Rock, and Roger Shepard,
perception
is a process of inference, and involves an analysis of
probabilities. The
brain’s task is to determine what the most likely arrangement of
objects
in the physical world is, given the particular pattern of
information that

86. reaches the sensory receptors—the retina for vision, the
eardrum for
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hearing. Most of the time the information we receive at our
sensory re-
ceptors is incomplete or ambiguous. Voices are mixed in with
other
voices, the sounds of machines, wind, footsteps. Wherever you
are right
now—whether you’re in an airplane, a coffee shop, a library, at
home, in
a park, or anywhere else—stop and listen to the sounds around
you. Un-
less you’re in a sensory isolation tank, you can probably
identify at least
a half-dozen different sounds. Your brain’s ability to make
these identifi-
cations is nothing short of remarkable when you consider what
it starts
out with—that is, what the sensory receptors pass up to it.
Grouping
principles—by timbre, spatial location, loudness, and so on—
help to

89. segregate them, but there is still a lot we don’t know about this
process;
no one has yet designed a computer that can perform this task of
sound
source separation.
The eardrum is simply a membrane that is stretched across
tissue and
bone. It is the gateway to hearing. Virtually all of your
impressions of the
auditory world come from the way in which it wiggles back and
forth in
response to air molecules hitting it. (To a degree, the pinnae—
the fleshy
parts of your ear—are also involved in auditory perception, as
are the
bones in your skull, but for the most part, the eardrum is the
primary
source of what we know about what is out there in the auditory
world.)
Let’s consider a typical auditory scene, a person sitting in her
living room
reading a book. In this environment, let’s suppose that there are
six

90. sources of sound that she can readily identify: the whooshing
noise of
the central heating (the fan or blower that moves air through the
duct-
work), the hum of a refrigerator in the kitchen, traffic outside
on the
street (which itself could be several or dozens of distinct sounds
com-
prising different engines, brakes squeaking, horns, etc.), leaves
rustling
in the wind outside, a cat purring on the chair next to her, and a
record-
ing of Debussy preludes. Each of these can be considered an
auditory
object or a sound source, and we are able to identify them
because each
has its own distinctive sound.
Sound is transmitted through the air by molecules vibrating at
certain
frequencies. These molecules bombard the eardrum, causing it
to wiggle
in and out depending on how hard they hit it (related to the
volume or
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93. amplitude of the sound) and on how fast they’re vibrating
(related to
what we call pitch). But there is nothing in the molecules that
tells the
eardrum where they came from, or which ones are associated
with
which object. The molecules that were set in motion by the cat
purring
don’t carry an identifying tag that says cat, and they may arrive
on the
eardrum at the same time and in the same region of the eardrum
as the
sounds from the refrigerator, the heater, Debussy, and
everything else.
Imagine that you stretch a pillowcase tightly across the opening
of a
bucket, and different people throw Ping-Pong balls at it from
different
distances. Each person can throw as many Ping-Pong balls as he
likes,
and as often as he likes. Your job is to figure out, just by
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94. the pillowcase moves up and down, how many people there are,
who
they are, and whether they are walking toward you, away from
you, or
are standing still. This is analogous to what the auditory system
has to
contend with in making identifications of auditory objects in the
world,
using only the movement of the eardrum as a guide. How does
the brain
figure out, from this disorganized mixture of molecules beating
against a
membrane, what is out there in the world? In particular, how
does it do
this with music?
It does this through a process of feature extraction, followed by
an-
other process of feature integration. The brain extracts basic,
low-level
features from the music, using specialized neural networks that
decom-
pose the signal into information about pitch, timbre, spatial
location,
loudness, reverberant environment, tone durations, and the

95. onset times
for different notes (and for different components of tones).
These oper-
ations are carried out in parallel by neural circuits that compute
these
values and that can operate somewhat independently of one
another—
that is, the pitch circuit doesn’t need to wait for the duration
circuit to be
done in order to perform its calculations. This sort of
processing—
where only the information contained in the stimulus is
considered by
the neural circuits—is called bottom-up processing. In the world
and in
the brain, these attributes of the music are separable. We can
change one
without changing the other, just as we can change shape in
visual objects
without changing their color.
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Low-level, bottom-up processing of basic elements occurs in the

98. pe-
ripheral and phylogenetically older parts of our brains; the term
low-
level refers to the perception of elemental or building-block
attributes of
a sensory stimulus. High-level processing occurs in more
sophisticated
parts of our brains that take neural projections from the sensory
recep-
tors and from a number of low-level processing units; this refers
to the
combining of low-level elements into an integrated
representation. High-
level processing is where it all comes together, where our minds
come to
an understanding of form and content. Low-level processing in
your
brain sees blobs of ink on this page, and perhaps even allows
you to put
those blobs together and recognize a basic form in your visual
vocabu-
lary, such as the letter A. But it is high-level processing that
puts together
three letters to let you read the word ART and to generate a

99. mental im-
age of what the word means.
At the same time as feature extraction is taking place in the
cochlea,
auditory cortex, brain stem, and cerebellum, the higher-level
centers of
our brain are receiving a constant flow of information about
what has
been extracted so far; this information is continually updated,
and typi-
cally rewrites the older information. As our centers for higher
thought—
mostly in the frontal cortex—receive these updates, they are
working hard
to predict what will come next in the music, based on several
factors:
~ what has already come before in the piece of music we’re
hearing;
~ what we remember will come next if the music is familiar;
~ what we expect will come next if the genre or style is
familiar,
based on previous exposure to this style of music;
~ any additional information we’ve been given, such as a
summary
of the music that we’ve read, a sudden movement by a

100. performer,
or a nudge by the person sitting next to us.
These frontal-lobe calculations are called top-down processing
and
they can exert influence on the lower-level modules while they
are per-
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forming their bottom-up computations. The top-down
expectations can
cause us to misperceive things by resetting some of the circuitry
in the
bottom-up processors. This is partly the neural basis for
perceptual com-
pletion and other illusions.
The top-down and bottom-up processes inform each other in an
on-
going fashion. At the same time as features are being analyzed
individu-
ally, parts of the brain that are higher up—that is, that are more
phylogenetically advanced, and that receive connections from
lower

103. brain regions—are working to integrate these features into a
perceptual
whole. The brain constructs a representation of reality, based on
these
component features, much as a child constructs a fort out of
Lego
blocks. In the process, the brain makes a number of inferences,
due
to incomplete or ambiguous information; sometimes these
inferences
turn out to be wrong, and that is what visual and auditory
illusions are:
demonstrations that our perceptual system has guessed
incorrectly
about what is out-there-in-the-world.
The brain faces three difficulties in trying to identify the
auditory ob-
jects we hear. First, the information arriving at the sensory
receptors is
undifferentiated. Second, the information is ambiguous—
different ob-
jects can give rise to similar or identical patterns of activation
on the
eardrum. Third, the information is seldom complete. Parts of the

104. sound
may be covered up by other sounds, or lost. The brain has to
make a cal-
culated guess about what is really out there. It does so very
quickly and
generally subconsciously. The illusions we saw previously,
along with
these perceptual operations, are not subject to our awareness. I
can tell
you, for example, that the reason you see triangles where there
are none
in the Kaniza figure is due to perceptual completion. But even
after you
know the principles that are involved, it is impossible to turn
them off.
Your brain keeps on processing the information in the same
way, and
you continue to be surprised by the outcome.
Helmholtz called this process “unconscious inference.” Rock
called it
“the logic of perception.” George Miller, Ulrich Neisser,
Herbert Simon,
and Roger Shepard have described perception as a “constructive
pro-

105. cess.” These are all ways of saying that what we see and hear is
the end
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of a long chain of mental events that give rise to an impression,
a mental
image, of the physical world. Many of the ways in which our
brains func-
tion—including our senses of color, taste, smell, and hearing—
arose due
to evolutionary pressures, some of which no longer exist. The
cognitive
psychologist Steven Pinker and others have suggested that our
music-
perception system was essentially an evolutionary accident, and
that
survival and sexual-selection pressures created a language and
commu-
nication system that we learned to exploit for musical purposes.
This is
a contentious point in the cognitive-psychology community. The
archae-
ological record has left us some clues, but it rarely leaves us a

108. “smoking
gun” that can settle such issues definitively. The filling-in
phenomenon
I’ve described is not just a laboratory curiosity; composers
exploit this
principle as well, knowing that our perception of a melodic line
will con-
tinue, even if part of it is obscured by other instruments.
Whenever we
hear the lowest notes on the piano or double bass, we are not
actually
hearing 27.5 or 35 Hz, because those instruments are typically
incapable
of producing much energy at these ultralow frequencies: Our
ears are fill-
ing in the information and giving us the illusion that the tone is
that low.
We experience illusions in other ways in music. In piano works
such
as Sindig’s “The Rustle of Spring” or Chopin’s Fantasy-
Impromptu in
C-sharp Minor, op. 66, the notes go by so quickly that an
illusory melody
emerges. Play the tune slowly and it disappears. Due to stream

109. segrega-
tion, the melody “pops out” when the notes are close enough
together in
time—the perceptual system holds the notes together—but the
melody is
lost when its notes are too far apart in time. As studied by
Bernard Lortat-
Jacob at the Musée de l’Homme in Paris, the Quintina (literally
“fifth
one”) in Sardinian a capella vocal music also conveys an
illusion: A fifth
female voice emerges from the four male voices when the
harmony and
timbres are performed just right. (They believe the voice is that
of the Vir-
gin Mary coming to reward them if they are pious enough to
sing it right.)
In the Eagles’ “One of These Nights” (the title song from the
album of
the same name) the song opens with a pattern played by bass
and guitar
that sounds like one instrument—the bass plays a single note,
and the
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112. guitar adds a glissando, but the perceptual effect is of the bass
sliding,
due to the Gestalt principle of good continuation. George
Shearing cre-
ated a new timbral effect by having guitar (or in some cases,
vibrophone)
double what he was playing on the piano so precisely that
listeners come
away wondering, “What is that new instrument?” when in
reality it is two
separate instruments whose sounds have perceptually fused. In
“Lady
Madonna,” the four Beatles sing into their cupped hands during
an in-
strumental break and we swear that there are saxophones
playing, based
on the unusual timbre they achieve coupled with our (top-down)
expec-
tation that saxophones should be playing in a song of this genre.
Most contemporary recordings are filled with another type of
audi-
tory illusion. Artificial reverberation makes vocalists and lead

113. guitars
sound like they’re coming from the back of a concert hall, even
when
we’re listening in headphones and the sound is coming from an
inch
away from our ears. Microphone techniques can make a guitar
sound
like it is ten feet wide and your ears are right where the
soundhole is—
an impossibility in the real world (because the strings have to
go across
the soundhole—and if your ears were really there, the guitarist
would be
strumming your nose). Our brains use cues about the spectrum
of the
sound and the type of echoes to tell us about the auditory world
around
us, much as a mouse uses his whiskers to know about the
physical world
around him. Recording engineers have learned to mimic those
cues to
imbue recordings with a real-world, lifelike quality even when
they’re
made in sterile recording studios.

114. There is a related reason why so many of us are attracted to
recorded
music these days—and especially now that personal music
players are
common and people are listening in headphones a lot. Recording
engi-
neers and musicians have learned to create special effects that
tickle our
brains by exploiting neural circuits that evolved to discern
important
features of our auditory environment. These special effects are
similar in
principle to 3-D art, motion pictures, or visual illusions, none of
which
have been around long enough for our brains to have evolved
special
mechanisms to perceive them; rather, they leverage perceptual
systems
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that are in place to accomplish other things. Because they use
these neu-
ral circuits in novel ways, we find them especially interesting.

117. The same
is true of the way that modern recordings are made.
Our brains can estimate the size of an enclosed space on the
basis of
the reverberation and echo present in the signal that hits our
ears. Even
though few of us understand the equations necessary to describe
how
one room differs from another, all of us can tell whether we’re
standing
in a small, tiled bathroom, a medium-sized concert hall, or a
large church
with high ceilings. And we can tell when we hear recordings of
voices
what size room the singer or speaker is in. Recording engineers
create
what I call “hyperrealities,” the recorded equivalent of the
cinematog-
rapher’s trick of mounting a camera on the bumper of a
speeding car. We
experience sensory impressions that we never actually have in
the real
world.

118. Our brains are exquisitely sensitive to timing information. We
are able
to localize objects in the world based on differences of only a
few mil-
liseconds between the time of arrival of a sound at one of our
ears ver-
sus the other. Many of the special effects we love to hear in
recorded
music are based on this sensitivity. The guitar sound of Pat
Metheny or
David Gilmour of Pink Floyd use multiple delays of the signal
to give an
otherwordly, haunting effect that triggers parts of our brains in
ways that
humans had never experienced before, by simulating the sound
of an en-
closed cave with multiple echoes such as would never actually
occur in
the real world—an auditory equivalent of the barbershop
mirrors that re-
peated infinitely.
Perhaps the ultimate illusion in music is the illusion of structure
and
form. There is nothing in a sequence of notes themselves that

119. creates the
rich emotional associations we have with music, nothing about a
scale, a
chord, or a chord sequence that intrinsically causes us to expect
a reso-
lution. Our ability to make sense of music depends on
experience, and
on neural structures that can learn and modify themselves with
each
new song we hear, and with each new listening to an old song.
Our brains
learn a kind of musical grammar that is specific to the music of
our cul-
ture, just as we learn to speak the language of our culture.
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Noam Chomsky’s contribution to modern linguistics and
psychology
was proposing that we are all born with an innate capacity to
understand
any of the world’s languages, and that experience with a
particular lan-
guage shapes, builds, and then ultimately prunes a complicated

122. and in-
terconnected network of neural circuits. Our brain doesn’t know
before
we’re born which language we’ll be exposed to, but our brains
and natu-
ral languages coevolved so that all of the world’s languages
share certain
fundamental principles, and our brains have the capacity to
incorporate
any of them, almost effortlessly, through mere exposure during
a critical
stage of neural development.
Similarly, it seems that we all have an innate capacity to learn
any of
the world’s musics, although they, too, differ in substantive
ways from
one another. The brain undergoes a period of rapid neural
development
after birth, continuing for the first years of life. During this
time, new
neural connections are forming more rapidly than at any other
time in
our lives, and during our midchildhood years, the brain starts to
prune

123. these connections, retaining only the most important and most
often
used ones. This becomes the basis for our understanding of
music, and
ultimately the basis for what we like in music, what music
moves us, and
how it moves us. This is not to say that we can’t learn to
appreciate new
music as adults, but basic structural elements are incorporated
into the
very wiring of our brains when we listen to music early in our
lives.
Music, then, can be thought of as a type of perceptual illusion
in
which our brain imposes structure and order on a sequence of
sounds.
Just how this structure leads us to experience emotional
reactions is
part of the mystery of music. After all, we don’t get all weepy
eyed when
we experience other kinds of structure in our lives, such as a
balanced
checkbook or the orderly arrangement of first-aid products in a
drug-

124. store (well, at least most of us don’t). What is it about the
particular kind
of order we find in music that moves us so? The structure of
scales and
chords has something to do with it, as does the structure of our
brains.
Feature detectors in our brains work to extract information from
the
stream of sounds that hits our ears. The brain’s computational
system
combines these into a coherent whole, based in part on what it
thinks it
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ought to be hearing, and in part based on expectations. Just
where those
expectations come from is one of the keys to understanding how
music
moves, when it moves us, and why some music only makes us
want to
reach for the off button on our radios or CD players. The topic
of musi-
cal expectations is perhaps the area in the cognitive

127. neuroscience of
music that most harmoniously unites music theory and neural
theory,
musicians and scientists, and to understand it completely, we
have to
study how particular patterns of music give rise to particular
patterns of
neural activations in the brain.
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What is music? To many, “music” can only mean the great
masters—Beethoven, Debussy, and Mozart. To others, “music”
is Busta
Rhymes, Dr. Dre, and Moby. To one of my saxophone teachers
at Berklee
College of Music—and to legions of “traditional jazz”
aficionados—
anything made before 1940 or after 1960 isn’t really music at
all. I had
friends when I was a kid in the sixties who used to come over to
my
house to listen to the Monkees because their parents forbade

132. them to lis-
ten to anything but classical music, and others whose parents
would
only let them listen to and sing religious hymns. When Bob
Dylan dared
to play an electric guitar at the Newport Folk Festival in 1965,
people
walked out and many of those who stayed, booed. The Catholic
Church
banned music that contained polyphony (more than one musical
part
playing at a time), fearing that it would cause people to doubt
the unity
of God. The church also banned the musical interval of an
augmented
fourth, the distance between C and F-sharp and also known as a
tritone
(the interval in Leonard Bernstein’s West Side Story when Tony
sings the
name “Maria”). This interval was considered so dissonant that it
must
have been the work of Lucifer, and so the church named it
Diabolus in
musica. It was pitch that had the medieval church in an uproar.

133. And it
was timbre that got Dylan booed.
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The music of avant-garde composers such as Francis Dhomont,
Robert Normandeau, or Pierre Schaeffer stretches the bounds of
what
most of us think music is. Going beyond the use of melody and
harmony,
and even beyond the use of instruments, these composers use
record-
ings of found objects in the world such as jackhammers, trains,
and wa-
terfalls. They edit the recordings, play with their pitch, and
ultimately
combine them into an organized collage of sound with the same
type of
emotional trajectory—the same tension and release—as
traditional mu-
sic. Composers in this tradition are like the painters who
stepped out-
side of the boundaries of representational and realistic art—the
cubists,

134. the Dadaists, many of the modern painters from Picasso to
Kandinsky to
Mondrian.
What do the music of Bach, Depeche Mode, and John Cage
funda-
mentally have in common? On the most basic level, what
distinguishes
Busta Rhymes’s “What’s It Gonna Be?!” or Beethoven’s
“Pathétique”
Sonata from, say, the collection of sounds you’d hear standing
in the
middle of Times Square, or those you’d hear deep in a
rainforest? As
the composer Edgard Varèse famously defined it, “Music is
organized
sound.”
This book drives at a neuropsychological perspective on how
music
affects our brains, our minds, our thoughts, and our spirit. But
first, it is
helpful to examine what music is made of. What are the
fundamental
building blocks of music? And how, when organized, do they

135. give rise to
music? The basic elements of any sound are loudness, pitch,
contour, du-
ration (or rhythm), tempo, timbre, spatial location, and
reverberation.
Our brains organize these fundamental perceptual attributes into
higher-
level concepts—just as a painter arranges lines into forms—and
these
include meter, harmony, and melody. When we listen to music,
we are ac-
tually perceiving multiple attributes or “dimensions.” Here is a
brief sum-
mary of them.
~ A discrete musical sound is usually called a tone. The word
note is
also used, but scientists reserve that word to refer to something
that is notated on a page or score of music. The two terms, tone
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and note, refer to the same entity in the abstract, where the
word
tone refers to what you hear, and the word note refers to what

138. you
see written on a musical score.
~ Pitch is a purely psychological construct, related both to the
actual
frequency of a particular tone and to its relative position in the
musi-
cal scale. It provides the answer to the question “What note is
that?”
(“It’s a C-sharp.”) I’ll define frequency and musical scale
below.
~ Rhythm refers to the durations of a series of notes, and to the
way
that they group together into units. For example, in the
“Alphabet
Song” (the same as “Twinkle, Twinkle Little Star”) the notes of
the
song are all equal in duration for the letters A B C D E F G H I
J K
(with an equal duration pause, or rest, between G and H), and
then
the following four letters are sung with half the duration, or
twice
as fast per letter: L M N O (leading generations of
schoolchildren
to spend several early months believing that there was a letter in

139. the English alphabet called ellemmenno).
~ Tempo refers to the overall speed or pace of the piece.
~ Contour describes the overall shape of a melody, taking into
ac-
count only the pattern of “up” and “down” (whether a note goes
up
or down, not the amount by which it goes up or down).
~ Timbre is that which distinguishes one instrument from
another—
say, trumpet from piano—when both are playing the same
written
note. It is a kind of tonal color that is produced in part by over-
tones from the instrument’s vibrations.
~ Loudness is a purely psychological construct that relates
(nonlin-
early and in poorly understood ways) to the physical amplitude
of
a tone.
~ Spatial location is where the sound is coming from.
~ Reverberation refers to the perception of how distant the
source is
from us in combination with how large a room or hall the music
is
What Is Music? 15

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142. in; often referred to as “echo” by laypeople, it is the quality that
distinguishes the spaciousness of singing in a large concert hall
from the sound of singing in your shower. It has an
underappreci-
ated role in communicating emotion and creating an overall
pleas-
ing sound.
These attributes are separable. Each can be varied without
altering
the others, allowing the scientific study of one at a time, which
is why we
can think of them as dimensions. The difference between music
and a
random or disordered set of sounds has to do with the way these
funda-
mental attributes combine, and the relations that form between
them.
When these basic elements combine and form relationships with
one an-
other in a meaningful way, they give rise to higher-order
concepts such

143. as meter, key, melody, and harmony.
~ Meter is created by our brains by extracting information from
rhythm and loudness cues, and refers to the way in which tones
are grouped with one another across time. A waltz meter orga-
nizes tones into groups of three, a march into groups of two or
four.
~ Key has to do with a hierarchy of importance that exists
between
tones in a musical piece; this hierarchy does not exist in-the-
world,
it exists only in our minds, as a function of our experiences
with a
musical style and musical idioms, and mental schemas that all
of
us develop for understanding music.
~ Melody is the main theme of a musical piece, the part you
sing
along with, the succession of tones that are most salient in your
mind. The notion of melody is different across genres. In rock
mu-
sic, there is typically a melody for the verses and a melody for
the
chorus, and verses are distinguished by a change in lyrics and
sometimes by a change in instrumentation. In classical music,

144. the
melody is a starting point for the composer to create variations
on
that theme, which may be used throughout the entire piece in
dif-
ferent forms.
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~ Harmony has to do with relationships between the pitches of
dif-
ferent tones, and with tonal contexts that these pitches set up
that
ultimately lead to expectations for what will come next in a
musi-
cal piece—expectations that a skillful composer can either meet
or violate for artistic and expressive purposes. Harmony can
mean
simply a parallel melody to the primary one (as when two
singers
harmonize) or it can refer to a chord progression—the clusters
of
notes that form a context and background on which the melody
rests.

147. The idea of primitive elements combining to create art, and of
the im-
portance of relationships between elements, also exists in visual
art and
dance. The fundamental elements of visual perception include
color
(which can be decomposed into the three dimensions of hue,
saturation,
and lightness), brightness, location, texture, and shape. But a
painting is
more than these—it is not just a line here and another there, or a
spot of
red in one part of the picture and a patch of blue in another.
What makes
a set of lines and colors into art is the relationship between this
line and
that one; the way one color or form echoes another in a
different part of
the canvas. Those dabs of paint and lines become art when form
and
flow (the way in which your eye is drawn across the canvas) are
created
out of lower-level perceptual elements. When they combine
harmoni-

148. ously they ultimately give rise to perspective, foreground and
back-
ground, emotion, and other aesthetic attributes. Similarly, dance
is not
just a raging sea of unrelated bodily movements; the
relationship of
those movements to one another is what creates integrity and
integrality,
a coherence and cohesion that the higher levels of our brain
process.
And as in visual art, music plays on not just what notes are
sounded, but
which ones are not. Miles Davis famously described his
improvisational
technique as parallel to the way that Picasso described his use
of a can-
vas: The most critical aspect of the work, both artists said, was
not the
objects themselves, but the space between objects. In Miles’s
case, he
described the most important part of his solos as the empty
space be-
What Is Music? 17

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151. tween notes, the “air” that he placed between one note and the
next.
Knowing precisely when to hit the next note, and allowing the
listener
time to anticipate it, is a hallmark of Davis’s genius. This is
particularly
apparent in his album Kind of Blue.
To nonmusicians, terms such as diatonic, cadence, or even key
and
pitch can throw up an unnecessary barrier. Musicians and critics
some-
times appear to live behind a veil of technical terms that can
sound pre-
tentious. How many times have you read a concert review in the
newspaper and found you have no idea what the reviewer is
saying? “Her
sustained appoggiatura was flawed by an inability to complete
the
roulade.” Or, “I can’t believe they modulated to C-sharp minor!
How
ridiculous!” What we really want to know is whether the music
was per-

152. formed in a way that moved the audience. Whether the singer
seemed to
inhabit the character she was singing about. You might want the
re-
viewer to compare tonight’s performance to that of a previous
night or a
different ensemble. We’re usually interested in the music, not
the techni-
cal devices that were used. We wouldn’t stand for it if a
restaurant re-
viewer started to speculate about the precise temperature at
which the
chef introduced the lemon juice in a hollandaise sauce, or if a
film critic
talked about the aperture of the lens that the cinematographer
used; we
shouldn’t stand for it in music either.
Moreover, many of those who study music—even musicologists
and
scientists—disagree about what is meant by some of these
terms. We
employ the term timbre, for example, to refer to the overall
sound or
tonal color of an instrument—that indescribable character that

153. distin-
guishes a trumpet from a clarinet when they’re playing the same
written
note, or what distinguishes your voice from Brad Pitt’s if you’re
saying
the same words. But an inability to agree on a definition has
caused the
scientific community to take the unusual step of throwing up its
hands
and defining timbre by what it is not. (The official definition of
the
Acoustical Society of America is that timbre is everything about
a sound
that is not loudness or pitch. So much for scientific precision!)
What is pitch? This simple question has generated hundreds of
scien-
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tific articles and thousands of experiments. Pitch is related to
the fre-
quency or rate of vibration of a string, column of air, or other
physical
source. If a string is vibrating so that it moves back and forth

156. sixty times
in one second, we say that it has a frequency of sixty cycles per
second.
The unit of measurement, cycles per second, is often called
Hertz (ab-
breviated Hz) after Heinrich Hertz, the German theoretical
physicist
who was the first to transmit radio waves (a dyed-in-the-wool
theoreti-
cian, when asked what practical use radio waves might have, he
report-
edly shrugged, “None”). If you were to try to mimic the sound
of a fire
engine siren, your voice would sweep through different pitches,
or fre-
quencies (as the tension in your vocal folds changes), some
“low” and
some “high.”
Keys on the left of the piano keyboard strike longer, thicker
strings
that vibrate at a relatively slow rate. Keys to the right strike
shorter, thin-
ner strings that vibrate at a higher rate. The vibration of these
strings dis-

157. places air molecules, and causes them to vibrate at the same
rate—with
the same frequency as the string. These vibrating air molecules
are what
reach our eardrum, and they cause our eardrum to wiggle in and
out at
the same frequency. The only information that our brains get
about the
pitch of sound comes from that wiggling in and out of our
eardrum; our
inner ear and our brain have to analyze the motion of the
eardrum in or-
der to figure out what vibrations out-there-in-the-world caused
the
eardrum to move that way.
By convention, when we press keys nearer to the left of the
keyboard,
we say that they are “low” pitch sounds, and ones near the right
side of
the keyboard are “high” pitch. That is, what we call “low” are
those
sounds that vibrate slowly, and are closer (in vibration
frequency) to the

158. sound of a large dog barking. What we call “high” are those
sounds that
vibrate rapidly, and are closer to what a small yip-yip dog might
make.
But even these terms high and low are culturally relative—the
Greeks
talked about sounds in the opposite way because the stringed
instru-
ments they built tended to be oriented vertically. Shorter strings
or pipe
organ tubes had their tops closer to the ground, so these were
called
the “low” notes (as in “low to the ground,”) and the longer
strings and
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tubes—reaching up toward Zeus and Apollo—were called the
“high”
notes. Low and high—just like left and right—are effectively
arbitrary
terms that ultimately have to be memorized. Some writers have
argued
that “high” and “low” are intuitive labels, noting that what we
call high-

161. pitched sounds come from birds (who are high up in trees or in
the sky)
and what we call low-pitched sounds often come from large,
close-to-
the-ground mammals such as bears or the low sounds of an
earthquake.
But this is not convincing, since low sounds also come from up
high
(think of thunder) and high sounds can come from down low
(crickets
and squirrels, leaves being crushed underfoot).
As a first definition of pitch, let’s say it is that quality that
primarily
distinguishes the sound that is associated with pressing one
piano key
versus another.
Pressing a piano key causes a hammer to strike one or more
strings
inside the piano. Striking a string displaces it, stretching it a
bit, and its
inherent resiliency causes it to return toward its original
position. But it
overshoots that original position, going too far in the opposite

162. direction,
and then attempts to return to its original position again,
overshooting it
again, and in this way it oscillates back and forth. Each
oscillation cov-
ers less distance, and, in time, the string stops moving
altogether. This is
why the sound you hear when you press a piano key gets softer
until it
trails off into nothing. The distance that the string covers with
each os-
cillation back and forth is translated by our brains into
loudness; the rate
at which it oscillates is translated into pitch. The farther the
string trav-
els, the louder the sound seems to us; when it is barely traveling
at all,
the sound seems soft. Although it might seem counterintuitive,
the dis-
tance traveled and the rate of oscillation are independent. A
string can
vibrate very quickly and traverse either a great distance or a
small one.
The distance it traverses is related to how hard we hit it—this

163. corre-
sponds to our intuition that hitting something harder makes a
louder
sound. The rate at which the string vibrates is principally
affected by its
size and how tightly strung it is, not by how hard it was struck.
It might seem as though we should simply say that pitch is the
same
as frequency; that is, the frequency of vibration of air
molecules. This is
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almost true. Mapping the physical world onto the mental world
is sel-
dom so straightforward. However, for most musical sounds,
pitch and
frequency are closely related.
The word pitch refers to the mental representation an organism
has
of the fundamental frequency of a sound. That is, pitch is a
purely psy-
chological phenomenon related to the frequency of vibrating air
mole-

166. cules. By “psychological,” I mean that it is entirely in our
heads, not in
the world-out-there; it is the end product of a chain of mental
events that
gives rise to an entirely subjective, internal mental
representation or
quality. Sound waves—molecules of air vibrating at various
frequen-
cies—do not themselves have pitch. Their motion and
oscillations can
be measured, but it takes a human (or animal) brain to map them
to that
internal quality we call pitch.
We perceive color in a similar way, and it was Isaac Newton
who first
realized this. (Newton, of course, is known as the discoverer of
the the-
ory of gravity, and the inventor, along with Leibniz, of calculus.
Like
Einstein, Newton was a very poor student, and his teachers
often com-
plained of his inattentiveness. Ultimately, Newton was kicked
out of

167. school.)
Newton was the first to point out that light is colorless, and that
con-
sequently color has to occur inside our brains. He wrote, “The
waves
themselves are not colored.” Since his time, we have learned
that light
waves are characterized by different frequencies of oscillation,
and
when they impinge on the retina of an observer, they set off a
chain of
neurochemical events, the end product of which is an internal
mental
image that we call color. The essential point here is: What we
perceive as
color is not made up of color. Although an apple may appear
red, its
atoms are not themselves red. And similarly, as the philosopher
Daniel
Dennett points out, heat is not made up of tiny hot things.
A bowl of pudding only has taste when I put it in my mouth—
when it
is in contact with my tongue. It doesn’t have taste or flavor
sitting in my

168. fridge, only the potential. Similarly, the walls in my kitchen are
not
“white” when I leave the room. They still have paint on them,
of course,
but color only occurs when they interact with my eyes.
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Sound waves impinge on the eardrums and pinnae (the fleshy
parts of
your ear), setting off a chain of mechanical and neurochemical
events,
the end product of which is an internal mental image we call
pitch. If a
tree falls in a forest and no one is there to hear it, does it make
a sound?
(The question was first posed by the Irish philosopher George
Berkeley.)
Simply, no—sound is a mental image created by the brain in
response to
vibrating molecules. Similarly, there can be no pitch without a
human or
animal present. A suitable measuring device can register the
frequency

171. made by the tree falling, but truly it is not pitch unless and until
it is
heard.
No animal can hear a pitch for every frequency that exists, just
as the
colors that we actually see are a small portion of the entire
electromag-
netic spectrum. Sound can theoretically be heard for vibrations
from just
over 0 cycles per second up to 100,000 cycles per second or
more, but
each animal hears only a subset of the possible sounds. Humans
who are
not suffering from any kind of hearing loss can usually hear
sounds from
20 Hz to 20,000 Hz. The pitches at the low end sound like an
indistinct
rumble or shaking—this is the sound we hear when a truck goes
by out-
side the window (its engine is creating sound around 20 Hz) or
when a
tricked-out car with a fancy sound system has the subwoofers
cranked

172. up really loud. Some frequencies—those below 20 Hz—are
inaudible to
humans because the physiological properties of our ears aren’t
sensitive
to them.
The range of human hearing is generally 20 Hz to 20,000 Hz,
but this
doesn’t mean that the range of human pitch perception is the
same; al-
though we can hear sounds in this entire range, they don’t all
sound mu-
sical; that is, we can’t unambiguously assign a pitch to the
entire range.
By analogy, colors at the infrared and ultraviolet ends of the
spectrum
lack definition compared to the colors closer to the middle. The
figure on
page 23 shows the range of musical instruments, and the
frequency as-
sociated with them. The sound of the average male speaking
voice is
around 110 Hz, and the average female speaking voice is around
220 Hz.
The hum of fluorescent lights or from faulty wiring is 60 Hz (in

173. North
America; in Europe and countries with a different
voltage/current stan-
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A27.500
30.863
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180. E
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181. 46.249
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182. 1244.5
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183. v
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Vi
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dard, it can be 50 Hz). The sound that a singer hits when she
causes a
glass to break might be 1000 Hz. The glass breaks because it,
like all
physical objects, has a natural and inherent vibration frequency.
You can
hear this by flicking your finger against its sides or, if it’s
crystal, by run-
ning your wet finger around the rim of the glass in a circular
motion.

186. When the singer hits just the right frequency—the resonant
frequency of
the glass—it causes the molecules of the glass to vibrate at their
natural
rate, and they vibrate themselves apart.
A standard piano has eighty-eight keys. Very rarely, pianos can
have a
few extra ones at the bottom and electronic pianos, organs, and
synthe-
sizers can have as few as twelve or twenty-four keys, but these
are spe-
cial cases. The lowest note on a standard piano vibrates with a
frequency
of 27.5 Hz. Interestingly, this is about the same rate of motion
that con-
stitutes an important threshold in visual perception. A sequence
of still
photographs—slides—displayed at or about this rate of
presentation
will give the illusion of motion. “Motion pictures” are a
sequence of still
images alternating with pieces of black film presented at a rate
(one
forty-eighth of a second) that exceeds the temporal resolving

187. properties
of the human visual system. We perceive smooth, continuous
motion
when in fact there is no such thing actually being shown to us.
When
molecules vibrate at around this speed we hear something that
sounds
like a continuous tone. If you put playing cards in the spokes of
your bi-
cycle wheel when you were a kid, you demonstrated to yourself
a related
principle: At slow speeds, you simply hear the click-click-click
of the
card hitting the spokes. But above a certain speed, the clicks run
to-
gether and create a buzz, a tone you can actually hum along
with; a pitch.
When this lowest note on the piano plays, and vibrates at 27.5
Hz, to
most people it lacks the distinct pitch of sounds toward the
middle of the
keyboard. At the lowest and the highest ends of the piano
keyboard, the
notes sound fuzzy to many people with respect to their pitch.

188. Composers
know this, and they either use these notes or avoid them
depending on
what they are trying to accomplish compositionally and
emotionally.
Sounds with frequencies above the highest note on the piano
keyboard,
around 6000 Hz and more, sound like a high-pitched whistling
to most
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people. Above 20,000 Hz most humans don’t hear a thing, and
by the age
of sixty, most adults can’t hear much above 15,000 Hz or so due
to a stiff-
ening of the hair cells in the inner ear. So when we talk about
the range
of musical notes, or that restricted part of the piano keyboard
that con-
veys the strongest sense of pitch, we are talking about roughly
three
quarters of the notes on the piano keyboard, between about 55
Hz and

189. 2000 Hz.
Pitch is one of the primary means by which musical emotion is
con-
veyed. Mood, excitement, calm, romance, and danger are
signaled by a
number of factors, but pitch is among the most decisive. A
single high
note can convey excitement, a single low note sadness. When
notes are
strung together, we get more powerful and more nuanced
musical state-
ments. Melodies are defined by the pattern or relation of
successive
pitches across time; most people have no trouble recognizing a
melody
that is played in a higher or lower key than they’ve heard it in
before. In
fact, many melodies do not have a “correct” starting pitch, they
just float
freely in space, starting anywhere. “Happy Birthday” is an
example of
this. One way to think about a melody, then, is as an abstract
prototype
that is derived from specific combinations of key, tempo,

190. instrumenta-
tion, and so on. A melody is an auditory object that maintains
its identity
in spite of transformations, just as a chair maintains its identity
when
you move it to the other side of the room, turn it upside down,
or paint it
red. So, for example, if you hear a song played louder than you
are ac-
customed to, you still identify it as the same song. The same
holds for
changes in the absolute pitch values of the song, which can be
changed
so long as the relative distances between them remain the same.
The notion of relative pitch values is seen readily in the way
that we
speak. When you ask someone a question, your voice naturally
rises in
intonation at the end of the sentence, signaling that you are
asking. But
you don’t try to make the rise in your voice match a specific
pitch. It is
enough that you end the sentence somewhat higher in pitch than
you be-

191. gan it. This is a convention in English (though not in all
languages—we
have to learn it), and is known in linguistics as a prosodic cue.
There are
similar conventions for music written in the Western tradition.
Certain
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sequences of pitches evoke calm, others, excitement. The brain
basis for
this is primarily based on learning, just as we learn that a rising
intona-
tion indicates a question. All of us have the innate capacity to
learn the
linguistic and musical distinctions of whatever culture we are
born into,
and experience with the music of that culture shapes our neural
path-
ways so that we ultimately internalize a set of rules common to
that mu-
sical tradition.
Different instruments use different parts of the range of
available

194. pitches. The piano has the largest range of any instrument, as
you can
see from the previous illustration. The other instruments each
use a sub-
set of the available pitches, and this influences the ways that
instruments
are used to communicate emotion. The piccolo, with its high-
pitched,
shrill, and birdlike sound, tends to evoke flighty, happy moods
regardless
of the notes it’s playing. Because of this, composers tend to use
the pic-
colo for happy music, or rousing music, as in a Sousa march.
Similarly, in
Peter and the Wolf, Prokofiev uses the flute to represent the
bird, and
the French horn to indicate the wolf. The characters’
individuality in
Peter and the Wolf is expressed in the timbres of different
instruments
and each has a leitmotiv—an associated melodic phrase or
figure that
accompanies the reappearance of an idea, person, or situation.
(This is